<template>
    <div>
        <h1>我是app组件</h1>
        {{ count }}
        <hr />
        <Child ref="childComp"/>
    </div>
</template>

<script>
import Child from "@/components/Child";
export default {
    name: "App",
    components: { Child },
    data() {
        return {
            count: 0,
        };
    },
    mounted() {
    //初始化的时候，在这里对某一个子组件绑定自定义事件
    console.log(this.$refs.childComp);
        this.$refs.childComp.$once("changeCount",this.changeCount);
    },
    methods: {
        changeCount(value) {
            console.log(value);
            this.count += value;
        },
    },
};
</script>
